Audiological characteristics of patients with auditory neuropathy spectrum disorder

OBJECTIVE To summarize the clinical characteristics and auditory test results of patients with auditory neuropathy spectrum disorder and to analyse the audiological characteristics. METHODS The onset age, diagnosis age, pure tone audiometry, tympanometry, auditory brainstem response, distortion product otoacoustic emission of sixty patients with auditory neuropathy spectrum disorder were retrospectively analyzed. RESULTS Thirty-four males and twenty-six females(56.7% versus 43.3%) were included. The age of onset of hearing loss ranged from 6 to 32 years old(mean=16.6, SD=4.7). Most of the patients were adolescence. The age of diagnosis with ANSD was 24.9±6.8 years old. Two patients were noted to have optic atrophy. All ANSD subjects were diagnosed with bilateral ANSD. The most common configuration of audiogram among 60 patients was peaked or saucer type(85.0%), with the peak usually occurring at 2000 or 4000 Hz.. The degree of hearing loss ranged from better than mild to severe, with 28 of the 120 ears(23.3%) having better than mild hearing loss, 59 ears(49.2%) mild hearing loss, 28 ears(23.8%) moderate hearing loss, 4 ears(3.3%) severe hearing loss, and only 1 ear(0.8%) profound hearing loss. One hundred and fifteen ears had type A tympanograms, three ears type As and two ears type Ad. 92 the affected ears had absent middle-ear muscle ref lexes(MEMRs). Twenty-nine ears showed some MEMRs at 1 k Hz; however, it should be noted that the thresholds were elevated. CONCLUSION Most patients suffered from auditory neuropathy spectrum disorder alone, while some also with other neurological diseases. Careful evaluation of hearing thresholds at all frequencies, in particular the low frequencies, is important for patients with ANSD.